Rav Aharon said the reason is because it is against Halacha. As did the other Gedolei Yisroel who voted against it, such as Rav Chaim Ozer, the Brisker Rav, Rav Elchonon and the Chazon Ish. Just because the second tier rabbis “outvote” the Gedolei Yisroel is irrelevant even though the organization unfortunately is run by quantitative majority.
But all that’s because the point, anyways. According to Rav Aharon, Rav Chaim Ozer, the Brisker Rav, Rav Elchonon and the Chazon Ish, what I wrote earlier in this thread is correct.